On June 18, the Defense Nuclear Facilities Safety Board sent a letter to the National Nuclear Security Administration and the Los Alamos National Laboratory, concerning the Plutonium Facility.

The letter laid out DNFSB concerns with identified deficiencies in Revision 1 of the 2011 Documented Safety Analysis for the Plutonium Facility. The Board requested a report and briefing within 30 days addressing the deficiencies.

This week, Don Cook, the deputy administrator for defense programs for NNSA, responded and said in a letter addressed to DNFSB chairman Peter Winokur that “in order to develop a response that adequately addresses the Board’s issues, the National Nuclear Security Administration and LANL need an additional 45 days beyond the requested 30-day timeframe.”

The biggest concern expressed by DNFSB officials surrounded what would happen in the event of a major earthquake. The board suggested that radiation released could be more than four times stronger than LANL, which is located near a number of fault lines, predicted in a safety analysis it released last year.

DNFSB also had a number of other concerns.

For example the board said the lab erroneously assumed that walls consisting of “gypsum board panels” — an apparent reference to drywall — would remain intact after an earthquake.

The board also found that the lab did not adequately consider the presence of combustible material in the facility. For example, the board said that the basement at PF-4 houses both combustible material and electrical panels that are not programmed to shut off in the event of an earthquake. Though the two could combine to ignite a fire in the basement, the lab assumed that the risk was “not credible,” the board said.

Additionally, the board, which might undergo budget cuts in the next fiscal year, said glove boxes at the facility feature shielding made of combustible material.

The lab did not fully account for the flammable shielding, the report said.

The DNFSB also accused the lab of underestimating the quantity of fine, “respirable” plutonium powder that would be released into the air. The board said the lab based its calculations on “an arbitrary factor” and the resulting estimate “cannot be technically justified.”

The lab considered only one fire breaking out in the aftermath of an earthquake even though PF-4 could be threatened by multiple fires breaking out simultaneously, the board said.

The board said “for one accident the mitigated dose (radiation) consequences to the public exceed 100 REM total effective dose equivalent (TEDE), which would require additional safety controls for the facility.”

Back in February, Cook wrote a letter to the DNFSB stating, “Our evaluation of the existing PF-4 facility in 2008 established a Documented Safety Analysis (DSA) for the facility that was compliant with the Department’s Nuclear Safety Rule.

“The DSA concluded that safety measures at PF-4 were reasonable and adequately protected the public under current standards for existing facilities. However, the evaluation highlighted that the facility was not as resilient and its safety systems were not as effective as we would require of a new facility constructed today.

“Therefore, taking the most conservative approach, we concluded that additional analysis and modifications to PF-4 were warranted to minimize the potential for a radiological release following an accident triggered by a rare earthquake and subsequent main-floor fire. Upon analysis, the actual risk to the public was so small, given the rarity of the earthquake and fire event, that NNSA concluded that it was prudent to allow continued operations while we took measures to modernize the facility.”